1. Field of the Invention
An embodiment of the present invention relates to an illumination apparatus incorporating a spatial modulation unit for generating a predetermined light intensity distribution (pupil luminance distribution) on an illumination pupil plane on the basis of light from a light source, an illumination method using the spatial modulation unit, an exposure apparatus incorporating the illumination apparatus, and a device manufacturing method using the exposure apparatus.
2. Related Background Art
A reflection-type spatial light modulator is hitherto known as a spatial modulator to form a pupil luminance distribution for modified illumination (e.g., a dipolar, quadrupolar, or other distribution) in exposure apparatus. Such a reflection-type spatial light modulator is described, for example, in Japanese Patent Application Laid-open No. 2002-353105 (Document 1).
There is also a recent trend to demand multilevel (3- or more-valued) distributions rather than a simple binary (presence/absence of light) distribution, as pupil luminance distributions for modified or off-axis illumination (e.g., cf. Patent Document 2: U.S. Pat. No. 6,466,304). In Document 2, a multilevel pupil luminance distribution is obtained by placing a spatial filter with a number of transparent regions composed of a semitransparent substrate and a masking film, in the illumination pupil plane.